<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <script src="jquery/jquery-3.1.1.min.js"></script>
    <script type="text/javascript" src="js/background.js"></script>
    <title>背景</title>
</head>
<body>
<h2>this is a heading</h2>
<p>this is a paragraph</p>
<p>this is another paragraph</p>
<ol>
    <li>1</li>
    <li>2</li>
    <li>3</li>
</ol>
<button  type="button">click me</button>
</body>
</html>